The present invention relates to a filter press and in particular to a displacement apparatus for separating and removing individual filter plates for cleaning, etc.
Various displacement devices have been known for use on filter presses, which individually displace each filter plate so that the periodic removal of the filter cake from the plate can be made, following the opening of the filter press. Envelope drives, particularly continuous chain drives, equipped with a separating mechanism, have been used for the displacement of the filter plates. Due, however, to the size and weight of the filter plates, two such envelope drives are generally provided, set either on each of the sides or above the filter plates. The separating mechanism generally comprises a plurality of movable pawls arranged on the chains constituting the envelope drives, which pawls hook in at a point provided on the filter plates and drive the latter. The chain drives continuously move or perform a reciprocating movement. In this connection, it is important that only a single filter plate be driven in each case. However, since the filter plates are pressed firmly against one another, and are coated with a cake which causes the plates to adhere to each other, it is possible that during the separation of one filter plate, by the pawl, one or more of the following filter plates are simultaneously displaced. That is, although it is intended to remove only a single plate at a time, two or more plates are frequently removed. This is prejudicial to the operating process since the cake is very difficult to remove from the adhering multiple plates. To avoid this condition, additional components have been generally used, which are intended to cooperate with the separating mechanism to prevent displacement of more than one filter plate at a time.
One known construction is disclosed in No. GB-A-1441, 316, wherein a pivotal pawl wheel is associated with each filter plate and engages with a rack, so that each filter plate is positively held in place. In order to displace the filter plate, the corresponding pawl wheel must be first released from the rack by pivoting the pawl. This means for locking each of the individual plates, however, represents a costly and complicated solution. It has furthermore been found that disengagement is not always reliable.
In another known construction shown in No. DE-Al-1295517, a continuous envelope drive is arranged on each side of the filter plate. This solution is also complicated and costly and it is not possible to retain or retard the following filter plate on the displacement of the first filter plate.
It is an object of the present invention to construct a filter plate displacement device, wherein there is no need for using special means on the driving mechanism for holding back the following or subsequent filter plates, so that as a result, the displacement device is simplified.
It is a further object, however, to provide a filter plate displacement device which insures positive displacement of the first, and only the first of the filter plates in the press.
The foregoing objects, together with other objects and advantages, are set forth in the following disclosure.